Method for preparing silica filled organosiloxane compositions

Abstract

The triorganosiloxydiphenylsilanols of the present invention are novel silicone compounds that are useful as plasticizers for silicone rubbers. The present invention also relates to a method for preparing these compounds in high yield and purity and a method for preparing filled curable organosiloxane compositions using the present compounds as plasticizers.

That which is claimed is: 
     
       1. In a method for preparing a filled organosiloxane composition by blending a curable polyorganosiloxane with an inorganic filler in the presence of a plasticizer selected from the group consisting of organosilicon compounds containing at least one silanol group per molecule, the improvement comprising selecting said plasticizer from among triorganosiloxydiphenyl-silanols of the general formula ##STR12## where C 6  H 5  designates the phenyl radical and each R is individually selected from the group consisting of substituted and unsubstituted monovalent hydrocarbon radicals. 
     
     
       2. A method according to claim 1 where the concentration of said plasticizer is from 0.05 to 20 weight parts per 100 weight parts of said curable polyorganosiloxane. 
     
     
       3. A method according to claim 2 where said composition includes an amount of a curing agent sufficient to cure said polyorganosiloxane.